The present invention relates to threaded fasteners, such as bolts, nuts and the like.
Threaded fasteners are known which include a bolt and a nut which has at least one sleeve and a washer. Such fasteners are disclosed for example in my U.S. patent application Ser. No. 09/033,790, in my U.S. Pat. Nos. 5,341,560 and 5,640,749. There are three types of threaded fasteners. In the threaded fasteners of one type, the washer is connected to the inner sleeve of the two-sleeve nut via splines. In the other type the washer is spline-connected to the bolt. In the third type the washer is not connected to the inner sleeve, and the reaction force of the tool is applied simultaneously to the washer and to the inner sleeve, or to the washer and to the bolt head.
The connection of the washer via splines to the inner sleeves or to the bolt is expensive to manufacture since it requires an outer spline and an inner spline. Manufacturing of the nut when the washer is not connected to the inner sleeve or the bolt is less expensive, but has the disadvantage that the washer needs connecting means on the outside for the tool to apply a reaction force to it, which is also costly. In addition, the later needs two reaction drives, one for the inner sleeve or the bolt end and one for the washer, which also increases its cost relative to the other type where merely one action and reaction drive is needed.
Accordingly, it is an object of present invention to provide a threaded connection of the above mentioned general type which avoids the disadvantages of the prior art.
In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated in a threaded fastener which has a bolt, a nut including at least one sleeve in which said bolt is threadingly engaged, and a washer having a lower bearing surface adapted to bank on a surface of one of at least two elements to be connected with one another by the threaded fastener, said washer having a smooth inner surface and being press-fit with said smooth inner surface on a smooth outer surface of a part of the threaded fastener, so that when an active force and an opposite reactive force are applied to parts of the threaded fastener, said washer does not turn, while said bolt also does not turn but moves only in an axial direction.
When the threaded fastener is designed in accordance with the present invention, the washer has a round inner female opening, so that the washer can be pressed-fitted onto a round portion of the other part of the threaded connector, for example on the round portion of the inner sleeve or the round portion of the bolt. The manufacturing cost of the nut of the threaded connector in accordance with the present invention is 25% lower than the manufacturing cost for the threaded connector with the spline-connection and by about 15% lower than that of the nut that requires two reaction shafts, since the outer diameter of the washer can be round.
In the threaded connector which has a nut including an outer sleeve and an inner sleeve, the active force is applied to the outer sleeve, while the opposite reactive force can be applied either to the inner sleeve or to the outside of the washer so that in the later case the connecting means on the inner sleeve for the reactive drive is not needed.
The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.